Absorption Properties of Supercooled Liquid Water between 31 and 225 GHz: Evaluation of Absorption Models Using Ground-Based Observations
ABSTRACT Microwave radiometers (MWR) are commonly used to quantify the amount of supercooled liquid water (SLW) in clouds; however, the accuracy of the SLW retrievals is limited by the poor knowledge of the SLW dielectric properties at microwave frequencies. Six liquid water permittivity models were...
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ftciteseerx:oai:CiteSeerX.psu:10.1.1.1044.9012 2023-05-15T16:29:56+02:00 Absorption Properties of Supercooled Liquid Water between 31 and 225 GHz: Evaluation of Absorption Models Using Ground-Based Observations Stefan Kneifel Stephanie Redl Emiliano Orlandi Ulrich Lö Hnert Maria P Cadeddu David D Turner The Pennsylvania State University CiteSeerX Archives application/pdf http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1044.9012 http://radiometrics.com/data/uploads/2012/08/kneifel_JAMC_2014.pdf en eng http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1044.9012 http://radiometrics.com/data/uploads/2012/08/kneifel_JAMC_2014.pdf Metadata may be used without restrictions as long as the oai identifier remains attached to it. http://radiometrics.com/data/uploads/2012/08/kneifel_JAMC_2014.pdf text ftciteseerx 2020-04-05T00:16:49Z ABSTRACT Microwave radiometers (MWR) are commonly used to quantify the amount of supercooled liquid water (SLW) in clouds; however, the accuracy of the SLW retrievals is limited by the poor knowledge of the SLW dielectric properties at microwave frequencies. Six liquid water permittivity models were compared with ground-based MWR observations between 31 and 225 GHz from sites in Greenland, the German Alps, and a low-mountain site; average cloud temperatures of observed thin cloud layers range from 08 to 2338C. A recently published method to derive ratios of liquid water opacity from different frequencies was employed in this analysis. These ratios are independent of liquid water path and equal to the ratio of a L at those frequencies that can be directly compared with the permittivity model predictions. The observed opacity ratios from all sites show highly consistent results that are generally within the range of model predictions; however, none of the models are able to approximate the observations over the entire frequency and temperature range. Findings in earlier published studies were used to select one specific model as a reference model for a L at 90 GHz; together with the observed opacity ratios, the temperature dependence of a L at 31.4, 52.28, 150, and 225 GHz was derived. The results reveal that two models fit the opacity ratio data better than the other four models, with one of the two models fitting the data better for frequencies below 90 GHz and the other for higher frequencies. These findings are relevant for SLW retrievals and radiative transfer in the 31-225-GHz frequency region. Text Greenland Unknown Greenland |
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ABSTRACT Microwave radiometers (MWR) are commonly used to quantify the amount of supercooled liquid water (SLW) in clouds; however, the accuracy of the SLW retrievals is limited by the poor knowledge of the SLW dielectric properties at microwave frequencies. Six liquid water permittivity models were compared with ground-based MWR observations between 31 and 225 GHz from sites in Greenland, the German Alps, and a low-mountain site; average cloud temperatures of observed thin cloud layers range from 08 to 2338C. A recently published method to derive ratios of liquid water opacity from different frequencies was employed in this analysis. These ratios are independent of liquid water path and equal to the ratio of a L at those frequencies that can be directly compared with the permittivity model predictions. The observed opacity ratios from all sites show highly consistent results that are generally within the range of model predictions; however, none of the models are able to approximate the observations over the entire frequency and temperature range. Findings in earlier published studies were used to select one specific model as a reference model for a L at 90 GHz; together with the observed opacity ratios, the temperature dependence of a L at 31.4, 52.28, 150, and 225 GHz was derived. The results reveal that two models fit the opacity ratio data better than the other four models, with one of the two models fitting the data better for frequencies below 90 GHz and the other for higher frequencies. These findings are relevant for SLW retrievals and radiative transfer in the 31-225-GHz frequency region. |
author2 |
The Pennsylvania State University CiteSeerX Archives |
format |
Text |
author |
Stefan Kneifel Stephanie Redl Emiliano Orlandi Ulrich Lö Hnert Maria P Cadeddu David D Turner |
spellingShingle |
Stefan Kneifel Stephanie Redl Emiliano Orlandi Ulrich Lö Hnert Maria P Cadeddu David D Turner Absorption Properties of Supercooled Liquid Water between 31 and 225 GHz: Evaluation of Absorption Models Using Ground-Based Observations |
author_facet |
Stefan Kneifel Stephanie Redl Emiliano Orlandi Ulrich Lö Hnert Maria P Cadeddu David D Turner |
author_sort |
Stefan Kneifel |
title |
Absorption Properties of Supercooled Liquid Water between 31 and 225 GHz: Evaluation of Absorption Models Using Ground-Based Observations |
title_short |
Absorption Properties of Supercooled Liquid Water between 31 and 225 GHz: Evaluation of Absorption Models Using Ground-Based Observations |
title_full |
Absorption Properties of Supercooled Liquid Water between 31 and 225 GHz: Evaluation of Absorption Models Using Ground-Based Observations |
title_fullStr |
Absorption Properties of Supercooled Liquid Water between 31 and 225 GHz: Evaluation of Absorption Models Using Ground-Based Observations |
title_full_unstemmed |
Absorption Properties of Supercooled Liquid Water between 31 and 225 GHz: Evaluation of Absorption Models Using Ground-Based Observations |
title_sort |
absorption properties of supercooled liquid water between 31 and 225 ghz: evaluation of absorption models using ground-based observations |
url |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1044.9012 http://radiometrics.com/data/uploads/2012/08/kneifel_JAMC_2014.pdf |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
http://radiometrics.com/data/uploads/2012/08/kneifel_JAMC_2014.pdf |
op_relation |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1044.9012 http://radiometrics.com/data/uploads/2012/08/kneifel_JAMC_2014.pdf |
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Metadata may be used without restrictions as long as the oai identifier remains attached to it. |
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